A variety trial was conducted in Wellton AZ, as part of the statewide upland variety testing program. It was designed to evaluate yield and yield quality parameters of several varieties provided by seed industry. The trial was made of conventional and transgenic varieties tested under growers' cultural practices. Preliminary results are subject to change when ginning and laboratory analysis is completed. The lint yield reported in this Farm Notes is based on the assumption that the turnout will be 35%. The lint results reported show three group of varieties, those that yielded 1800 lb or higher, those between 1600 and 1800 lb and the remaining group with yield below 1600 lb per acre.

Introduction
While cotton acreage tends to stabilize in Yuma County between 22000 to 25000 acres, in recent years, yield is changing. Cotton growers are no longer rewarded for the total yield they harvest from their fields. They are also compensated for the high quality lint they produce or penalized for poor quality. One of the determinant factors among the environmental variables and agronomic practices affecting yield and lint quality includes the choice of variety adapted to the cotton growing area. The objective of this experiment was to evaluate the performance of several varieties developed by cotton seed industry.

Methods
An experimental field was selected on silt loam soil in Wellton, AZ, to conduct upland cotton variety trial. Twelve varieties provided by six companies were planted on grower's field on March 20, 2003 in a six-row plot, 40" bed spacing replicated three times. Cotton was planted on wet field. All agronomic practices were similar to all varieties based on grower's management practices. Cotton field received a total of 7 irrigations during the growing season on 5-15, 5-31, 6-14, 6-23, 7-5, 7-14, and 7-24-03. Urea was side dressed at 165 lb per acre on 5-14-03. Additional application was made on 6-03-03; water run at 10 gal per acre (lb/A). On 5-26-03 Mepiclor pill was banded at ½ pint per acre, and Mepex was applied on 6-12-03 at 1 pint per acre. Insect control was made with Knack applied 10 oz per acre on 7-11-03, followed by Warrior applied at 5 oz per acre and Orthene applied at 1 lb per acre on 7-19-03. Cotton was defoliated with Ginstar applied at 8 oz per acre and 6 oz per acre on 8-27-03.

Two rows of cotton were harvested and weighed using boll buggy equipped with electronic scale to determine seed and lint weight. The remaining rows were left for the field day on 9-9-03. Fifteen pound sub-samples were collected from each plot for the ginning and fiber quality analysis. In this Farm Note, we report total seed and lint yield for each variety and lint yield calculated on the assumption that the turnout is 35% that is subject to change.

Results
Preliminary results are reported in Table 1. Lint yield is subject to change after the ginning and laboratory analysis are made. The lint yield is calculated based on the assumption that the turn out is expected to be 35%. The results are therefore only preliminary until the actual turnout is determined from the gin. In addition, the fiber, strength, length and micronaire are needed from the laboratory to include in the final ranking.

Table 1. Seed and lint, lint preliminary upland cotton variety trial results--Wellton AZ site, 2003. Yield lint is calculated assuming 35% turnout

All varieties tested appeared to have reasonable yield, the lowest variety had 1587 lb per acre and the highest was 1986 lb per acre. Based on these preliminary results, varieties are grouped into 3 categories, the first group of varieties includes those with yield 1800 lb or higher, those with yield between 1600 and 1800 lb per acre and those below 1600 lb per acre.

Full Disclaimers

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture and Life Sciences, The University of Arizona.

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